This invention relates to thermoplastic injection molding and, more particularly, it relates to an improved transfer system for guiding a thermoplastic injection runner from a conveyor into a collection hopper.
In the formation of plastic parts by means of thermoplastic injection, a connecting web or runner of plastic material is formed connecting the parts being molded. The resulting runner and parts being molded are fed onto a conveyor for movement to a collection point. The molded parts, such as closures, are normally vibrated loose from the runner as they are transported on the conveyor. These parts are then deposited into a collection device at the end of the conveyor. The plastic material in the runner is capable of being recycled if it can be recovered without damage or contamination. The prior art has included a transfer drum which incorporated spikes thereon for picking up the runner as it reaches the end of the conveyor for transferring into a hopper attached to a grinder. It has been found, however, that the use of such a spiked transfer drum has resulted in the runner becoming wrapped around the transfer roll or dropping to the floor. In the former case, the process must be stopped while the runner is disengaged from the transfer drum. In the latter case, the runner, which has dropped to the floor, may become contaminated and nonreuseable for recycling purposes.